1. Field of the Invention
Geothermal Well Head Assembly.
2. Description of the Prior Art
In recent years, due to the uncertainty of petroleum and natural gas as a source of energy, the production of power from geothermal wells has taken on increased importance. A troublesome problem in the production of geothermal energy, is maintaining a seal at the well head between the ambient atmosphere and the interior of the valved manifold through which the heated fluid from the geothermal zone flows. The difficulty in so maintaining a seal is due to the substantial longitudinal expansion and contraction that takes place in the casing or tubing string through which heated fluid flows relative to the stationary well head assembly. In the past it has been common practice to employ multiple groups of resilient rings to effect a seal to allow for such expansion and contraction, with the groups of rings having the same force exerted thereon to radially expand the same. Such a mode of sealing has been found unsatisfactory in that there was no correlation between the forces exerted on the two groups of resilient rings, and as a result an excessive force could be exerted on one group and an insufficient force on the other group.
A major object of the present invention is to supply a geothermal well head assembly that allows longitudinal expansion and contraction of the string of casing or tubing operatively associated therewith and that extends to a fixed position relative to the producing zone without the operational disadvantages of prior art devices of this nature, and one in which a single force producing mechanism operated from the exterior of the well head assembly deforms a first group of resilient rings into slidable sealing contact with the hot fluid carrying string and concurrently the same force moves a second group of resilient rings that provide a secondary seal downwardly relative to a downwardly and inwardly tapering surface to effect a seal therewith.
Another object of the invention is to provide a geothermal well head assembly that is simple and easy to use, and one that requires the actuation of but a single force producing mechanism to place the assembly in a condition where there is no undesired communication between the ambient atmosphere and the interior of the assembly.
Yet another object of the invention is to supply a geothermal well head assembly that is of simpler structure than prior art devices of this nature, and one that requires a minimum of maintenance attention.
Yet another object of the invention is to provide a geothermal well head assembly in which the first and second sealing rings may periodically have the compressive force exerted thereon adjusted manually from the exterior of the assembly without shutting down the well by pumping mud down the bore hole. After such a shut down the well may not return to its original productivity, and in some instances be killed due to the mud impregnating the geothermal zone.